Space heating furnaces have been known previously and are useful for heating structures, particularly where the source of the heat is electrical energy. Frequently, space heating furnaces will contain heat storage units which are chargeable during "off peak" hours of electricity demand, in order to take advantage of lower electrical energy expenses. These space heating furnaces are then able to generate a sufficient volume of heat to satisfactorily charge the heat storage units at an economical cost to the individuals. Subsequently, during peak demand hours during which high rates are charged for energy, room air is moved through the furnace to be heated, and thus returned to the room for space heating.
When room air is moved through a furnace and heated the quality of the heated room air may be diminished due to odors which occur as a result hydrocarbon "cracking." Hydrocarbon "cracking" occurs when air is exposed to extreme temperatures. Odors will exist when room air is directly exposed to an extreme heat source and then recirculated back into a structure.
One form of space heating furnace is disclosed in the Barabas, et al. U.S. Pat. No. 4,234,782 which illustrates the use of "off peak" electricity to heat alkaline metal or alkaline earth metal salts which are used as a heat storage device. Heating of a structure occurs with the circulation of room air through the heat storage device and then back into the structure.
The Manning U.S. Pat. No. 4,631,388 shows another form of heating system which illustrates the use of "off peak" electricity to heat a stack of bricks which are thermally connected to a vessel containing a liquid to be heated by a controllable heat pipe.
Other forms of space heat furnaces and heat storing devices are illustrated in U.S. Pat. Nos. 4,714,821, 4,006,734, 4,094,302, and 3,381,113.